Study On The Influence Of Green Building Envelope Structure On Heat Consumption

The high-performance enclosure structure is a widely used passive energy-saving technology.The green building requires that the thermal performance of the external wall,the outer window,the roof and other locations should be at least 5% higher than the national energy-saving standard limit.The requirements in the standard are even higher.The continuously updated energy-saving standards and related policies are guiding the gradual increase of the thermal performance of the envelope structure,whether the increase in energy consumption and the cost increase are reasonable,and there is no relevant analysis and discussion on the rationality of such trends.In this paper,the thermal performance improvement of the green building envelope is the focus of research,and the prototype building model in severe cold and cold regions is established.The calculation of the thermal performance of the enclosure is analyzed by the method of computational simulation plus actual testing.The impact of the quantitative analysis of the main influencing factors,the establishment of a multiindicator design choice method for the envelope structure.According to the limit requirements of energy-saving standards,two types of prototype buildings in severe cold and cold regions were established.Through the calculation and simulation method,it was concluded that the increase of thermal performance has a certain exponential relationship with the thermal load per unit area of the building.The exponential equation can calculate the predicted value.The heat load formed by the outer window is the most common in the thermal load of all the envelope structures,the specific gravity is 40%-70%,the outer wall is second,the specific gravity is 20%-40%,and the roof is the least.The common practices of green building envelopes in cold and cold areas were summarized,and the thermal performance improvement under different types of insulation layers,thickness and external window types was quantitatively analyzed,and the environmental impact and economic cost of the whole life cycle caused by the improvement were analyzed..When the thickness of the rock wool used for the outer wall reaches 100 mm and the thickness of the roof is 200 mm,the thermal performance improvement rate of the outer wall begins to stabilize;when the thermal performance of the outer wall and the roof is increased by less than 60% and 40% respectively,Environmental impact loads and economic costs are minimal.The influence of the thermal performance improvement of 10 green building envelopes on the actual heat consumption of the building was analyzed.The concept of integrated heat loss coefficient is improved to analyze the effect of thermal performance of the envelope on the actual heat consumption of the building.Through the method of verifying the model,the sensitivity coefficients of various parts of the external wall,roof and exterior window are simulated and the influence degree of thermal performance at different positions of the envelope structure is comprehensively analyzed.The result is outer window(IC)>outer wall(IC)> Roofing(IC).The selection principle of multi-index evaluation and two types of building multi-index database in different climate zones were constructed.Under the premise of improving the thermal performance as an important indicator,and prioritizing economic costs,and selecting the enclosure structure with small environmental impact load,the specific practices of exterior walls,exterior windows and roofs are recommended.